Refractory coatings are often employed to enhance wear resistance, corrosion resistance, performance and/or lifetime of various tooling and machinery. TiN, TiC, TiCN and Al2O3, for example, have been applied to tooling surfaces by CVD and physical vapor deposition (PVD). In many applications, TiN is applied to tooling and machinery by PVD. However, PVD techniques suffer a significant disadvantage in that they can only coat surfaces in line-of-sight from the source. Further, PVD techniques generally suffer from low coating growth rates. These disadvantages render difficult the efficient and complete coating of parts having complex geometries, resulting in low product yield.
CVD techniques are largely unrestricted by line-of-sight requirements and provide conformal coverage with higher growth rates and higher loading factors. Nevertheless, CVD techniques generally require high temperatures unsuitable for many heat-treated metal or alloy substrates. Exposure of heat-treated substrates to high CVD temperatures can degrade mechanical properties of the substrate and induce undesirable structural or phase transitions in the metal or alloy.